Communication controlling apparatus for a single-line telephone with extensions thereto

Abstract

In a single-line telephone, there are a plurality of extension telephone sets connected by a telephone line and each extension telephone set is connected to a communication controlling apparatus. The communication controlling apparatus includes an alternating current coupler and a power supply thus allowing two extension telephone sets to communicate with each other without being disturbed by a busy tone.

I claim: 
     
       1. A communication controlling apparatus for a single-line telephone with extension telephone sets connected thereto, where the extension telephone sets are electrically connected by a telephone line and the communication controlling apparatus is connected to a corresponding extension telephone set, the communication controlling apparatus comprising: a preprogrammed microprocessor;   a relay driving means being connected to the microprocessor and the extension telephone set; and connecting the telephone line with the extension telephone set;   an alternating current coupler being connected between the relay driving means and the telephone line for isolating a busy tone from the telephone line thus allowing the extension telephone set to have an intercom telephone communication with another extension telephone set without being disturbed by the busy tone;   an on-line detecting means being electrically connected between the microprocessor and the extension telephone set for detecting a status of the extension telephone set which is either picked up or hung up and sending a status indicative signal to inform the microprocessor of the status of the extension telephone set;   a pulse detecting means for detecting a call-in signal from any one of other extension telephone sets via the telephone line and sending a detecting signal to the microprocessor in response;   an on-line holding means for holding an external call-in signal on the telephone line;   a pulse outputting circuit being connected to and driven by the microprocessor to send a call-out signal to other extension telephone sets via the telephone line;   a power supply which is connected to and activated by the microprocessor for providing required working power to the relay driving circuit;   a setting switch being connected to the microprocessor for setting a number corresponding to this extension telephone set;   a key array being connected to the microprocessor for inputting either a transferring command or a dialing number of a destination extension telephone set to the microprocessor to command the microprocessor to execute a corresponding action;   whereby the extension telephone set is electrically connected to the telephone line via the relay driving means but not via the alternating current coupler when the extension telephone set is not picked up, but when the extension telephone set is picked up, the extension telephone set is electrically connected to the telephone line via the alternating current coupler and the relay driving means.   
     
     
       2. The communication controlling apparatus as claimed in claim 1 further comprising a line status detecting circuit for detecting whether or not a destination extension telephone set is being picked up when an external call-in signal is transferred from the extension telephone set to the destination extension telephone set, and to release the on-line holding means circuit when the destination extension telephone set is picked up. 
     
     
       3. The communication controlling apparatus as claimed in claim 2 further comprising an on-line answering circuit which is driven by the microprocessor to send out an answering ring via the telephone line to inform the received party that this extension telephone set is still on line when the external telephone call is being held. 
     
     
       4. The communication controlling apparatus as claimed in claim 1 further comprising a buzzer triggering means which is driven by the microprocessor to inform the user of this extension telephone set of a call from another extension telephone set.